Tuning and Setting SIF Test Intervals

Each Equipment-Actor can have multiple proof Tests. These are defined on the Equipment level. The aim is to set an interval for each of these Tests, which ensures an Achieved PFD < Target PFD (see Calculating SIF Achieved PFD and Verifying Integrity).

Optimizing the Test Intervals

To calculate / refresh the optimized Test Intervals:

• Set all your Optimization Parameters.
• Click Optimize TI.
  Click Test Interval Tuning. 
• This will calculate the optimized Test Intervals, set all Test Intervals accordingly, and calculate the Achieved PFD.

Setting the TI Optimization Parameters

A number of parameters can be used to influence the Test Interval optimization. These are shown below and explained in the following table. Taken note that they will not apply when the interval is locked. In this case the optimization TI is overwritten by a user set value.

Image Caption

The TI Optimization parameters:

TI Optimization parameter icon	Description
	When shown like this, the Subsystem's Test Intervals will not be aligned. Click this if you want all Test Intervals in the Subsystem to be aligned. The icon will then change to indicate that the intervals are being aligned: .
	When shown like this, all SIFs using this Actuator are considered in the Optimization. Hover over the icon to see which SIFs that is. If you do not want to include these SIFs in the TI Optimization, click on the icon to indicate this. The icon will then indicate that the SIFs are not considered:.
	This is the Interval Constraints. To set constraints, click on the icon. If any constraints are set the icon will show this: .
	This can be used to indicate when on-line testing is not possible, i.e., the process must be disrupted.

To override an Interval:

• Click on the applicable Test Interval link.Click on the applicable Test’s interval link. 
• Check Override required. (The lock will then also change from unlocked to locked.)
• Select a different Test Interval from the dropdown.
• Click Save.This TI is overwritten. It shows that it is locked and the optimization parameters are grey.